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Poster: Administrator, Curator, or StaffRod Hewitt Date: Oct 28, 2003 10:34pm
Forum: movies Subject: Re: Guidelines for making real video files

When the Prelinger films were converted to Real, we first took the MPEG files, resized them to 320x240 (1/4 NTSC on a square pixel display) and wrote them as uncompressed AVI files which were then fed into Real Producer 8.5 (Helix wasn't released then).

Since there were hundreds of files to convert, this was all done by a simple script and we used the command-line conversion tool, RMBatch. We made two versions - one for broadband and one for modem users.

For the broadband, these were the switches used:

/I file.avi - input filename
/O file.rm - output filename
/T 6,7,8 - target: 256K, 384K, 512K
/A 1 - audio: voice with background music
/V 0 - video: normal motion
/F 1 - SureStream (multi-rate requiring a RealServer)
/R 1 - Allows RealPlayer Plus users to record
/K 1 - Allows downloading
/Q "Brought to you by the Internet Archive" - the title

For the modem users, the video was scaled to 160x120 and the rate was changed, so these were the switches:

/I file.avi - input filename
/O file.rm - output filename
/T 0,1,2,3,4,5 - 28K, 56K, single ISDN, dual ISDN, DSL/cable modem, corporate LAN
/OS 160,120 - resize to 160x120
/RZ 1 - high quality resize
/A 1 - audio: voice with background music
/V 0 - video: normal motion
/F 1 - SureStream (multi-rate requiring a RealServer)
/R 1 - Allows RealPlayer Plus users to record
/K 1 - Allows downloading
/Q "Brought to you by the Internet Archive" - the title

HTH,
Rod

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Poster: JeffT Date: Oct 29, 2003 2:01am
Forum: movies Subject: Re: Guidelines for making real video files

Hi Rod,
Thanks for that reply.

Can you give the rationale behind the speed choices made for each file? For example, why speeds faster than 56k in the dialup file when that is the top modem speed? Also, what happens if someone with a "150 kbps" DSL connection tries to use the broadband file? Since the slowest stream on the broadband file is 256 kbps, won't it fail when they try to view it?

Do you know of a real video document that gives guidelines for such things? I couldn't find it in their "production guide" but maybe I didn't know where to look.

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Poster: Administrator, Curator, or StaffRod Hewitt Date: Oct 29, 2003 2:37am
Forum: movies Subject: Re: Guidelines for making real video files

We made those choices based on looking at streams at various rates using the bandwidth simulator that's included with Real Producer. At anything below 256Kbps, the frame rate gets too low at 320x240, so for anyone with less than 256Kbps they get a very small image but at least the frame rate is there.

For dialup users, we decided not to include anything below 56Kbps because of picture quality (or rather lack of it - you get the sound, but only a frame a second at best).

Keep in mind that when you make these files with the SureStream stuff turned on, you'll end up with a bigger file than one would expect because these files contain multiple bitrate streams. The Real Server and Real Player negotiate the data rate depending initially on the user's connection speed and then alter it up or down depending on network conjestion.

If you play a broadband (256Kbps and up) stream on a connection lower than 256Kbps, the user will see Real Player do a lot of buffering, play a few seconds and then back to buffering - not a great experience.

I don't think there's any particular document that deals with this issue - at least none that I read hence I used the bandwidth simulator to figure out what rates/resultion we should use.

Rod

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Poster: JeffT Date: Oct 29, 2003 5:00am
Forum: movies Subject: Re: Guidelines for making real video files

I'm a little confused. The above post says: "For dialup users, we decided not to include anything below 56Kbps." Yet the earlier post gives the parameters used to make the dialup file as:
/T 0,1,2,3,4,5 - 28K, 56K, single ISDN, dual ISDN, DSL/cable modem, corporate LAN
Isn't the 28K below 56K?

Also, why have speeds faster than 56K for the dialup? Is the destinction between "dialup" and "broadband" not necessarily that dialup file users will be using a dialup modem, but that there had to be two different sizes (320x240 for higher bandwidth; 160x120 for lower bandwidth) and the speeds included in each file were what looked best in the simulator? In other words, it is expected that someone with a broadband connection slower than 256 kbps will use the "dialup" file rather than the broadband file?

Another way to ask this is: for the parameters used to generate the files, would it be more precise to name them, "slower than 256Kbps" and "256Kbps or faster", rather than "dialup" and "broadband"?

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